class

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Classes -

Class Object / Instance This Reference Constructors Encapsulation Mutators & Accessors

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Class

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Student -Name -Major

Obj

Student A

Obj

Obj

Student D

Student C

Obj

Student B

Class

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int x, y, z; char a, b, c; String nm, lastNm;

Class Car

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Class Car Car ! %, &'), *!, +),-./&0"%1, "# 24!"5678, 9:,);)4!")<"1, &,/,

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Class public class Person { private long idCard; private String nm, lastNm; public void setIdCard(long idCard) public void setNm(String nm) public void setLastNm(String lastNm) public long getIdCard() public String getNm() public String getLastNm() }

data

method

Object or Instance

',2L:JZ'G14[ .6 $G่:I6# 14$1516 Class '#)่4G่Z>.#<4 - %& G01Z- Class 6)< ' I \ $ Car

- !"#% - &') - *! - +),-./&0"%1 +.-7)#), +D% #6<1 +.E&/

Car1 Car 1

Car2 Car 2

Car3 Car 3

- Toyota - Corolla - -:, - 1600 +.-7)#), +D% #6<1 +.E&/

- Honda - Civic - .4, - 1800 +.-7)#), +D% #6<1 +.E&/

- Nissan - Cefiro - E&%)K - 2000 +.-7)#), +D% #6<1 +.E&/

Instance Variables

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Car - !"#% - &') - *! - +),-./&0"%1

Car1 Car 1 - Toyota - Corolla - -:, - 1600

Car2 Car 2 - Honda - Civic - .4, - 1800

Car3 Car 3 - Nissan - Cefiro - E&%)K - 2000

Static Variables

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Static Variables 8<;M2&+%1 Class Car - count = 0 - !"#% - &') - *! - +),-./&0"%1

?

Car1 Car 1

Car2 Car 2

Car3 Car 3

- Toyota - Corolla - -:, - 1600

- Honda - Civic - .4, - 1800

- Nissan - Cefiro - E&%)K - 2000

setCount(1) setCount(1 getCount()

setCount(2 setCount(2) getCount()

setCount(3 setCount(3) getCount()

- Object

61 O61_ [<modifier>] <ClassName> ref_nm; L2,&!14 public Car myCar; 61 # 14 // main class ref_nm = new <ClassName>([arguments]); L2,&!14 myCar = new Car(); - %& Car myCar = new Car();

Object S,&.&! STUďœ‹+ďœ‹%VW6 #&0% /'X*VE<87+%1 Object I ."" ref_nm.dataName; L2,&!ďœŠ14 // main class Car myCar = new Car(); String carColor = myCar.color; int carMfgYear = myCar.mfgYear; * 61 !6Z>ďœ‹+ďœ‹&$I=+&4 Object Lďœ‹&4L ,5#&" 4%ŕšˆ&';++&4 modifier Z-ďœ‹:I6Lďœ‹&4

Object S,&.&! STUďœ‹ method 4<";Y2+%1 Object I ."" ref_nm.methodName([arguments]); L2,&!ďœŠ14 // main class Car myCar = new Car(); String carColor = myCar.getColor();// return String value myCar.doBreak();// void method * 61 !6Z>ďœ‹ method +&4 Object Lďœ‹&4L ,5#&" 4%ŕšˆ&';++&4 modifier Z-ďœ‹:I6Lďœ‹&4

Static S,&.&! STUďœ‹+ďœ‹%VW64!".2ďœ’) static variable I ."" ref_nm.dataName; ClassName.dataName; L2,&!ďœŠ14 // main class Car myCar = new Car(); String carColor = myCar.color;// call through ref_nm - %& String carColor = Car.color;// call through className

Static S,&.&! STUďœ‹ method 4!".2ďœ’) static variable I ."" ref_nm.methodName([arguments]); ClassName.methodName([arguments]); L2,&!ďœŠ14 // main class Car myCar = new Car(); String carColor = myCar.getCount();// call through ref_nm - %& String carColor = Car.getCount();// call through className

: Scope of variable Car private static int count; private String carColor; method setColor(String color) String color

method break() int speed;

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: Scope of variable

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The this Reference : this

61 Z> this 5O:I6Z> $%่& object L&461 &14&)4:84L2, &4 [<!#,'Z-s5O '61 Z>Z' method +&4 object Z'6 K G่L2,. Z' method $>%่&F้0162"L2,. +&4 object (instance variable) public class Car { private String color; public void setColor(String color) { this.color = color; } }

Constructors

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Constructor public class Car { private String color;

public class Car { private String color;

public Car() { color = “Black�; } public Car(String color) { this.color = color; }

Car() { color = “Black�; } Car(String color) { this.color = color; }

}

}

Car myCar = new Car();

Car myCar = new Car(“Blue�);

Encapsulation

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Encapsulation : Black box Encapsulate field & method Object encapsulated

Client

+ďœ‹&$I= / HJK#$"2L) data / property

(PL)6 $ / 61 6 OG01 behavior / method

Encapsulation : Visibility Modifiers

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Encapsulation : Visibility Modifiers .+,D^1Y-9,S

public

protected default private

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Mutators and Accessors

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Mutators and Accessors public class Car { private String color; public void setColor(String color) { // setter method this.color = color; } public String getColor() { // getter method return color; } }

Program public class Car { private String color, brand; private int year; public void setColor(String color) { this.color = color; } public void setBrand(String brand) { this.brand = brand;} public void setYear(int year) { this.year = year; } public String getColor() { return color; } public String getBrand() { return brand; } public int getYear() { return year; } }

Program public class TestCar { public static void main(String[] args) { Car myCar = new Car(); myCar.setColor(“Black�); myCar.setBrand(“Honda�); myCar.setYear(2009); System.out.println(“Color of my car is � + myCar.getColor()); System.out.println(“Brand of my car is � + myCar.getBrand()); System.out.println(“Year of my car is � + myCar.getYear()); } }

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